The polystyrene resin particles according to the present invention are specifically flame retardant-containing polystyrene resin particles, foamable polystyrene resin particles for producing a heat-insulating material for building materials, foamable polystyrene resin particles for producing a banking member, and foamable polystyrene resin particles for producing a vehicle interior material. Hereinafter, these will be simply referred to by a general term of “foamable polystyrene resin particles” in some cases as necessary.
Hitherto as foamable polystyrene resin particles containing a flame retardant, for example, techniques disclosed in Patent Documents 1 to 3 have been suggested in the related art.
Patent Document 1 (Japanese Patent Application, First Publication No. 63-172744) discloses a process for producing a flame-retarding foamed styrene-based resin, which includes adding an organic solvent solution that contains 1.0 part by mass to 10 parts by mass of a bromine-based flame retardant having a predetermined structure and a foaming agent to 100 parts by mass of a styrene-based resin, and heating and foaming this mixture.
Patent Document 2 (Japanese Patent Application, First Publication No. 11-130898) discloses a process for producing a self-extinguishing polystyrene resin particles, which is characterized by including dispersing tetrabromobisphenol A diallyl ether such that the particle size becomes 50 μm or less in the presence of a surfactant, and then impregnating polystyrene resin particles with this dispersion as well as a softening; agent, a flame-retarding aid, a plasticizer, and a foaming agent. Patent Document 2 also discloses a molded article obtained using the resin particles.
Patent Document 3 (Published Japanese Translation No. 2001-525001 of the PCT International Publication) discloses a particle-like expandable styrene polymer containing evenly distributed graphite powder, and self-extinguishing foam obtained by treating the polymer. Patent Document 3 also discloses that the treatment can produce self-extinguishing foam which contains, as a flame retardant, an organic bromine compound including 70% by mass or more of bromine and passes a combustion test B2 (according to DIN 4102). As the organic bromine compound, hexabromocyclododecane, pentabromomonochlorocyclohexane, and pentabromophenylallyl ether are disclosed.
In addition, an insulation method is known. In this method, in order to improve an insulation performance in houses and the like, heat-insulating materials are installed between joists in a floor or between supporting members such as pillars or said walls. As the heat-insulating materials used for such an insulation method, glass wool has been widely used in general. However, the insulating effect of glass wool easily deteriorates since glass wool is hygroscopic. Accordingly, a high insulating effect over a long time cannot be expected, and there are problems in workability. For these reasons, recently, this type of insulating material has begun to be substituted with a polystyrene resin foam-molded article that is excellent in dimensional stability and a heat-insulating property.
The heat-insulating material for building materials is generally required to have a flame-retarding performance of a certain level or higher, from the viewpoints of preventing fire or the like, preventing spread of tire resulting from flame spreading in tire, and the like. In order to impart a sufficient flame-retarding performance to the polystyrene resin foam-molded article, a flame retardant is used by being added to foamable polystyrene resin particles for producing foamed molded articles.
The insulating material for building materials is required to have a water proofing property, an anti-hygroscopic property, moisture resistance, and a heat-insulating property. Moreover, the insulating material is also required not to expand or contract with temperature change (dimensional stability).
In addition, in order to counteract sick house syndrome that has been an increasing trend in recent years, the insulating material for building materials is required to reduce the amount of volatile organic compounds released. Examples of causative compounds of sick house syndrome include, as volatile organic compounds (VOC) for which the Ministry of Health, Labour and Welfare has established a guideline amount, formaldehyde, acetaldehyde, toluene, xylene, ethylbenzene, styrene, and the like.
Hitherto, as learnable polystyrene resin particles used as insulating materials for building materials, for example, a technique disclosed in Patent Document 4 (Japanese Patent Application, First Publication No. 2003-64212) has been suggested in the related art.
Patent Document 4 discloses foamable polystyrene resin particles which contain, in 100 parts by mass of foamable polystyrene resin particles, 350 ppm to 1200 ppm of a styrene monomer, 0.1 parts by mass to 2 parts by mass of a plasticizer that cannot be distilled at 250° C. or lower when vacuum distillation is performed under a pressure of 6.666×10−4 MPa mmHg), and a foaming agent.
Moreover, hitherto, a bank using foamed synthetic resin blocks has been widely used as the bank on weak ground, for slopes, or for an artificial hill in a garden, and used for embedding or backfiliing of an underground structure. As foam used for these members, polystyrene resin foams are used in many cases from the viewpoints of strength, water resistance, and the like. Among these, foamed molded articles are generally used which are produced in an in-mold foam molding method which includes pre-foaming foamable polystyrene resin particles (also referred to as beads) by heating, filling the obtained prefoamed particles in a cavity of a mold, and performing foaming by heating and molding in the mold.
The banking member is generally required to have a flame-retarding performance of a certain level or higher, from the viewpoints of preventing fire or the like, preventing the ground from becoming unstable due to flame spreading, and the like. In order to impart a sufficient flame-retarding performance to the polystyrene resin foam-molded article, a flame retardant is used by being added to the foamable polystyrene resin particles for producing the foamed molded article.
Hitherto, as methods of adding a flame retardant to the polystyrene resin foam-molded article, there have been a method of adding a flame retardant together with a styrene-based monomer during polymerization (for example, see Patent Document 4), and a method of simultaneously adding a flame retardant and a foaming agent when polystyrene resin particles are impregnated with the foaming agent, so as to produce foamable polystyrene resin particles by impregnating the polystyrene resin particles with the flame retardant and the foaming agent (for example, see Patent Documents 5 to 7: Japanese Patent Application, First Publication No. 2003-335891, Japanese Patent Application, First Publication No. 2002-194130, and Japanese Patent No. 4035979).
Moreover, hitherto, as interior materials of various vehicles such as automobiles, synthetic resin products have been widely used. Although non-foamed products are also used as the synthetic resin products, vehicle interior materials formed of synthetic resin foam-molded article are widely used, for the purposes of improving ride comfort by enhancing shock absorbing properties, protecting passengers by absorbing shock, securing flatness in a vehicle, and the like. As such foam-molded articles, various resins such as foamable urethane and foamable polystyrene are used. However, foamable polystyrene resin is widely used since this resin is excellent in moldability and functionality. In addition, examples of vehicle interior materials using the foamable polystyrene resin include automobile interior materials, particularly, a floor spacer, a door pad, a toolbox, and the like.
The vehicle interior material is generally required to have a flame-retarding performance of a certain level or higher, from the viewpoints of preventing tire or the like and a self-extinguishing property. In order to impart a sufficient flame-retarding performance to the polystyrene resin foam-molded article, a flame retardant is used by being added to foamable polystyrene resin particles for producing the foam-molded article.
In addition, in order to counteract the sick house syndrome described above, the vehicle interior materials are strongly required to contain an extremely small amount of volatile organic compounds.
Hitherto, regarding the reduction of the volatile organic compounds in the foamable polystyrene resin, for example, a technique disclosed in Patent Document 8 (Japanese Patent Application, First Publication No. 11-106548) has been suggested,
Patent Document 8 discloses styrene-based foamable resin particles which contain 1 ppm to 300 ppm of a residual styrene monomer, 1 ppm or less of benzene, 0.1% by mass to 2% by mass of a plasticizer that is compatible with styrene and has an SP value of 7 to 10, and a foaming agent.
In addition, Patent Document 4 discloses learnable polystyrene resin particles which contain, in 100 parts by mass of the foamable polystyrene resin particles, 350 ppm to 1200 ppm of a styrene monomer, 0.1 parts by mass to 2 parts by mass of a plasticizer that cannot be distilled at 250° C. or lower when vacuum distillation is performed under a pressure of 6.666×10−4 MPa (5 mmHg), and a foaming agent.
Furthermore, Patent Document 9 (Japanese Patent Application, First Publication No. 2007-169408) discloses styrene-based foamable resin particles which includes hexabromocyclododecane or tetrabromobisphenol A-bis(2,3-dibromopropyl ether) as the flame retardant and includes 4% by mass to 8% by mass of bromine derived from the flame retardant or the like.